Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net earnings	$ 19,768	$ 18,783
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	12,549	10,836
Stock compensation expense	2,181	1,631
Deferred income taxes	135	35
Provision for doubtful accounts	522	88
Foreign currency transaction (gain)/loss	(23)	50
Asset impairment charge	0	114
Gain on disposal of assets	0	(2,719)
Changes in assets and liabilities
Accounts receivable	(13,516)	(912)
Inventories	528	(139)
Prepaid expenses and other current assets	(349)	972
Accounts payable and accrued expenses	(3,098)	(12,389)
Income taxes	4,523	6,575
Other	(655)	(442)
Net cash provided by operating activities	22,565	22,483
Cash flows from investing activities:
Capital expenditures and intangible assets acquired	(5,394)	(8,507)
Proceeds from insurance	0	2,727
Net cash used in investing activities	(5,394)	(5,780)
Cash flows from financing activities:
Proceeds from revolving loan	10,000	0
Principal payments on revolving loan	(5,000)	(16,000)
Proceeds from stock options exercised	4,435	288
Dividends paid	(16,704)	(15,135)
Purchase of treasury stock	(891)	(727)
Net cash used in financing activities	(8,160)	(31,574)
Effect of exchange rate changes on cash	(724)	(393)
Increase (decrease) in cash and cash equivalents	8,287	(15,264)
Cash and cash equivalents beginning of period	65,672	54,268
Cash and cash equivalents end of period	$ 73,959	$ 39,004